The human rights group accused Syrian troops of using at least 156 cluster bombs in 119 locations throughout Syria between August and mid-February. In the past two weeks, Human Rights Watch investigated two cluster bomb attacks in Deir Jamal and Talbiseh. The attacks killed 11 civilians and injured 27 others, CNN reports.

"Syria is expanding its relentless use of cluster munitions, a banned weapon, and civilians are paying the price with their lives and limbs," Steve Goose, the director of the arms division at Human Rights Watch, said, according to CNN. "The initial toll is only the beginning because cluster munitions often leave unexploded bomblets that kill and maim long afterward."

In October, Syria's armed forces denied the possession or use of cluster bombs.

Amnesty International, another human rights group, made a similar accusation of cluster bomb use on Thursday.

"Civilians continue to be at the receiving end of increasingly frequent indiscriminate attacks by Syrian government forces," Amnesty International said, according to CNN. "Internationally banned cluster munitions are being used daily against civilian residential areas in towns and villages, in utter disregard for the most fundamental principles of international humanitarian law."

Amnesty International said that while most of the abuses were committed by Syrian government groups, rebel groups are engaged in abuses such as summary executions and kidnappings.

Syria is not one of the 111 countries worldwide signed up to the Convention on Cluster Munitions, which bans the use of cluster bombs. The United States is likewise not a signatory of the convention, CNN reports.